title: Extracellular proteases from Xanthomonas campestris pv. campestris, the black rot pathogen.
abstract: Two proteases (PRT1 and PRT2) were fractionated from culture supernatants of wild-type Xanthomonas campestris pv. campestris by cation-exchange chromatography on SP-5PW. Inhibitor experiments showed that PRT 1 was a serine protease which required calcium ions for activity or stability or both and that PRT 2 was a zinc-requiring metalloprotease. PRT 1 and PRT 2 showed different patterns of degradation of beta-casein. The two proteases comprised almost all of the extracellular proteolytic activity of the wild type. A protease-deficient mutant which lacked both PRT 1 and PRT 2 showed considerable loss of virulence in pathogenicity tests when bacteria were introduced into mature turnip leaves through cut vein endings. This suggests that PRT 1 and PRT 2 have a role in black rot pathogenesis.
authors.affiliation: Sainsbury Laboratory, John Innes Centre for Plant Science Research, Norwich, United Kingdom.
authors.forename: J M
authors.initials: JM
authors.lastname: Dow
authors.forename: B R
authors.initials: BR
authors.lastname: Clarke
authors.forename: D E
authors.initials: DE
authors.lastname: Milligan
authors.forename: J L
authors.initials: JL
authors.lastname: Tang
authors.forename: M J
authors.initials: MJ
authors.lastname: Daniels
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D010935:Plant Diseases; D012697:Serine Endopeptidases / Q000302:isolation & purification*; D015842:Serine Proteinase Inhibitors; D013379:Substrate Specificity; D014774:Virulence; D014974:Xanthomonas / Q000201:enzymology* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D015842:Serine Proteinase Inhibitors; D012697:Serine Endopeptidases; D008666:Metalloendopeptidases